Device for leak-tight transfer of objects

ABSTRACT

A DEVICE FOR LEAK-TIGHT TRANSFER OF NUCLEAR FUEL PELLETS FROM A GLOVE BOX TO A FUEL CAN. IT COMPRISES A TUBE WHICH PROJECTS THROUGH THE WALL OF THE BOX, THE INTERNAL DIAMETER OF THE TUBE CORRESPONDING TO THE INTERNAL DIAMETER OF THE CAN. A TAPE FORMED WITH HOLES HAVING A DIAMETER WHICH CORRESPONDS TO THE INTERNAL DIAMETER OF THE TUBE IS CIRCULATED FROM THE EXTERIOR TO THE INTERIOR OF THE BOX ALONG A PATH WHICH CAUSES THE HOLES TO PASS BETWEEN THE TUBE AND THE CAN.

Feb. 20, 1973 M. GODART DEVICE FUR LEAK-TIGHT TRANSFER OF OBJECTS Filed March 4, 1970 United States Patent 3,717,267 DEVICE FOR LEAK-TIGHT TRANSFER OF OBJECTS Michel Godart, Aix-en-Provence, France, assignor to Commissariat a llEnergie Atomique, Paris, France Filed Mar. 4, 1970, Ser. No. 16,411 Claims priority, application France, Mar. 10, 1969, 6906778 Int. Cl. B65g 65 /32 U.S. Cl. 214-17 B 7 Claims ABSTRACT OF THE DISCLOSURE This invention is concerned with a device for the leaktight transfer of objects to a container through an enclosure wall, said device being of particular interest in the case of contaminating and especially radioactive objects.

The invention is also directed to a method of transfer for the practical application of said device.

The problem of leak-tight transfer arises in particular whenever it proves necessary to convey an object towards an external container through an alpha-tight enclosure such as a glove box, the interior of which is contaminated. Such a problem is encountered especially when fuel pellets containing plutonium are transferred from a contaminated cell to cans which are to be loaded with fuel. In this case, the pellets have to be transferred from the contaminated glove box to the can without contaminating either the exterior of the can or the glove box in which this latter is placed. These conditions are met by the device which was described and claimed in French Pat. No. 1,499,227.

This device essentially comprises a tube which is fixed so as to penetrate through the wall in leak-tight manner, a funnel placed within the tube and having the same crosssectional area as the container to be filled so as to permit of exact location in the line of extension of this latter, a flexible tubular connection which closely surrounds the oppositely facing extremities of the funnel and of the container, and a shield envelope which surrounds the flexible connection and can be rigidly fixed to the extremity of the container.

However, this device is subject to disadvantages in that it does not completely remove all danger of contamination of the edge or end face of the container which is located opposite to the funnel. In point of fact, and in the case of fuel element cans, for example, a sealing end-cap is subsequently placed on the end face and closed by welding along the edge and must therefore be decontaminated prior to positioning of the end-cap.

Moreover, the embodiment which is described by way of example in French Pat. No. 1,499,227 is not readily suited to full automation.

Finally, the preparation of the can prior to coupling and filling is a relatively complex operation.

The present invention is intended to provide a leaktight transfer device which meets practical requirements more effectively than comparable devices of the prior art, especially insofar as it is. not subject to the disadvantages mentioned above. To this end, the invention proposes a device which permits leak-tight transfer of objects through an enclosure wall to a container and comprises a tube which penetrates through the wall and is attached thereto in leak-tight manner, the internal diameter of the tube being such as to correspond to the internal diameter of an opening of the container. Said device is essentially constituted by a tape pierced by holes having a diameter which corresponds to the internal diameter of the tube and by means for transferring the tape from the exterior to the interior of the enclosure along a path which causes the holes to pass between the tube and the container.

A better understanding of the invention will be gained from the following description of one particular embodiment which is given hereinafter by Way of example but without any implied limitation. The description refers to the single accompanying figure which is a sectional view along the vertical mid-plane of a device for effecting leak-tight transfer of nuclear fuel pellets from the interior of a glove box constituting the enclosure to fuel-pin cans.

The leak-tight transfer device is mounted so as to pass through the wall 2 which forms a separation between a contaminated glove box 4 constituting the enclosure and a clean or uncontaminated glove box 6. The atmosphere of the contaminated glove box 4 is maintained at a slightly negative pressure (a few millimeters of mercury) relative to the atmosphere of the uncontaminated glove box 6. This latter is in turn maintained at a negative pressure relative to the surrounding atmosphere. The transfer device proper comprises a funnel 8 consisting of a cylindrical tube having an internal diameter which corresponds to the internal diameter of each can 12 for receiving fuel pellets 14 which are stored in the contaminated glove box 4.

The internal end portion of the funnel 8 (namely that portion which is located within the contaminated glove box 4) is flared so as to facilitate introduction of the pellets 14. The funnel 8 is attached to the wall 2 in leaktight manner by means of a bushing 16 and clamping screws 18. One or a number of seals are evidently provided between the funnel 8 and the members which are associated therewith.

The external end portion of the funnel 8 (namely which is located in the glove box 6) opens into a compartment 20 which is limited by the wall 2 and by a recessed backing plate 24. Said compartment 20 is adapted to communicate with the uncontaminated glove box through an aperture 26 having a small cross-sectional area which is placed at one end of the compartment. Said compartment 20 is also adapted to communicate with the contaminated glove box through a slot 28 which is placed at the other end of this compartment.

The compartment 20 also communicates with the uncontaminated glove box 6 through a bore 30 which is coaxial with the funnel 8 and has a diameter which is slightly larger than that of the cans 12.

The device according to the invention comprises a mechanism for transferring a sealing tape 32 within the compartment along a path which causes it to pass between the outer extremity of the funnel 8 and the edge or end face of each can 12 which is positioned in turn. Said tape-transfer mechanism comprises a payoff reel 34 which is placed within the uncontaminated glove box 6, a guide roller 36, a tape guide 38 which is attached to the wall 2, a flat passageway 40 for-med in the plate 24 at the same end as the aperture 26 and a takeup reel 42.

As shown in the figure, the tape 32 is transferred from the uncontaminated glove box to the contaminated glove box and provides a separation between the funnel 8 of the uncontaminated glove box and the edge of the can when this later is maintained opposite to the funnel. Said tape is swept by the gas which emanates from the uncontaminated glove box and this gas flow tends to return dust particles to the glove box 4, and the contaminated portion of the tape.

The tape 32 is pierced at uniform intervals by circular holes 44 having a diameter corresponding to the internal diameter both of the funnel and of the cans. The hole spacing is preferably of the order of five times the diameter -(50 mm. in respect of a diameter of mm., for example). The takeup reel 42 is provided with drive means so that, each time said means are actuated, the tape 32 is displaced by an interval corresponding to one-half the pitch of the holes formed in the tape. Said tape consists of a film of material which is sufiiciently deformable to ensure absolute leak-tightness when the tape is pressed between the terminal portion of the funnel 8 and the end face of a can 12; a thin film of polyester material having high tensile strength and known by the trade name Mylar is particularly suited to this purpose.

The means for driving the takeup reel can be of any known type provided that the necessary standards of accuracy and operational safety are complied with. It is possible in particular to employ a system of the type known as a Geneva movement or maltese cross mechamsm.

The unncontaminated glove box 6 also contains a device for carrying out the movement of aproach and centering of cans as well as maintaining these latter against the tape 32 with a sufiicient pressure to apply the tape against the outer extremity of the funnel 8. The device which is illustrated comprises a feed arm 46 (as shown in chain-dotted lines) provided with a displacement mechanism which is not shown in the drawings and a fixed chunk 48 which is coaxial with the funnel. Clamping and releasing of the chuck are controlled by a cone '50 carried by a shaft 52 which is rotatable in bearings (not shown). The shaft terminates in a spur pinion 54 which is adapted to engage with a drive rack 56. The contaminated glove box 4 contains a trough 58 for feeding and guiding the pellets 14. Said pellets can be displaced through the funnel 8 towards a can 12 through a hole of the tape 32 by means of a push-rod which is not ilustrated.

The method according to the invention is apparent from the construction of the device which has been explained in the foregoing and will therefore be described only very briefly.

The contaminated glove box 4 contains acertain number of pellets which are fabricated, for example, from mixed uranium and plutonium oxide and are placed on guide troughs 58, one of which is aligned with the funnel 8. The tape 32 is moved to a position such that a full portion of wall is placed opposite to the funnel 8, a hole 44 being located on each side of said portion.

Gas is discharged from the uncontaminated glove box towards the slot 28 and the contaminated glove box 4 -as a result of the pressure dilference. The first can to be loaded is then brought by means of the arm 46 into the position illustrated in chain-dotted lines in the figure. The tape 32 is then displaced by one-half pitch by means of the rnachanism which drives the takeup reel 42. A hole of the tape 32 is then located opposite to the funnel 8 and to the can 12. The can is inserted so as to apply the tape 32 around the hole 44 against the outer end face of the funnel, thereby forming a leak-tight joint between the funnel 8 and the can 12. In order to ensure eltective leak-tightness, the tape can advantageously consist of a Mylar film.

The fuel pellets 14 are then inserted in the can 12 either once or a number of times, the chuck 48 is then caused to open so as to release the can, whereupon the can is moved back over a short distance and freed from the tape 32. The drive mechanism of the takeup reel 42 is then immediately actuated so as to displace the tape by one-half pitch so that a full portion is again located opposite to the funnel. The can which is loaded with fuel is then removed, its closure end-cap being preferably placed in position immediately in order to prevent any contamination. A new can is brought into position and again subjected to the same sequence.

It is readily apparent that the method hereinabove described prevents any contamination both of the glove box which is occupied by the cans and of the end faces of the cans 12. A continuous gas flow is established from the uncontaminated glove box towards the contaminated glove box and thus carries back any dust particles which might otherwise diffuse to the exterior. Each fresh can which is brought into position is put into contact with a clean portion of the tape 32, thereby preventing contamination of the end face whilst the contaminated portion of the tape is removed towards the contaminated glove box.

The device which as been described can evidently be associated with conventional automation circuits. The device can also be equipped with removable elements (not shown) which provide a leak-tight separation between the two glove boxes during those periods when the device is not in use. For example, these elements can comprise covers which are screwed on the bushing 18 and also or alternatively screwed on an end-piece which is provided for this purpose on the plate 24 (but is not shown in the drawings).

I claim:

1. In a device for the leak-tight transfer of objects from an enclosure towards a container through a wall of the enclosure, comprising a tube which sealingly projects through the wall and the internal diameter of which corresponds to the internal diameter of an opening of the container, a tape formed with holes corresponding in diameter to the internal diameter of the tube and means for transferring the tape from the exterior to the interior of the enclosure along a path which causes the holes to pass between said tube and said container.

2. A device according to claim 1, wherein the tape is a film of polyester material having high tensile strength.

3. A device according to claim 1, wherein said tube opens into a compartment which is connected to the enclosure by means of a slot through which the tape passes towards said enclosure and to the outside by means of a passageway for guiding the tape towards said compartment.

4. A device according to claim 3, wherein the enclosure is at a pressure lower than that of the outside and wherein the compartment is connected to the outside by an aperture located in proximity to the tape admission slot so as gas circulates along the tape towards said enclosure.

5. A device according to claim 1, wherein the means for transferring the tape comprise a takeup reel located within the enclosure and a mechanism for forward displacement of the reel by steps equal to one-half the spacing between two successive holes of the tape.

6. A device according to claim 1, comprising means References Cited for displacing said container towards and away from UN S ATES PA NTS the tube and means for locking the container in a posi- 2,873,160 1 5 Board 14 B X tion in which it presses said tape against a radial end face 5 3,137,397 6/1964 Nicoll et a1 2l4-17 B X of the tube.

7. A device according to claim 1, wherein said con- ROBERT SHERIDAN Pnmary Exammer tainer is a nuclear fuel-pin can, said enclosure is a glove US, Cl, X R

box and said objects are fuel pellets containing plutonium. 34-242; 53-244 

